Grzegorczyk hierarchy vs Iterated differential equations?
#1
Inspired by JmsNxn's thread (http://math.eretrandre.org/tetrationforu...39#pid7139) about the continuum sum I repost this obsevation about the link between the fractional calculus and the Hyperoperations.
I guess that there can be interesting links... and probably is not the wrong way to approach the problem. I just found some results about something similar.

M. Campagnolo, C. Moore -Upper and Lower Bounds on
Continuous-Time Computation


In this text I found a relation betwen a hierarchy of real valued function and the Grzegorczyk hierarchy.

The interesting relations are betwen a hierarchy called \( \mathcal{G}_n+\theta_k \) and the hierarchy \( \mathcal{E}_n \):

Quote:1-Any function in \( \mathcal{G}_n+\theta_k \) is computable in \( \mathcal{E}_n \)

2-If \( f\in \mathcal{G}_n+\theta_k \) then \( f \) is the extension to the reals of some \( f^{*}:\mathbb{N}\rightarrow\mathbb{N} \) then \( f^{*}\in \mathcal{E}_n \)

3-the converse holds: if \( f \) is a function on the naturals of rank \( n \) it has an extension in \( \mathcal{G}_n+\theta_k \)

-------------------
The interesting thing is that the various levels of \( \mathcal{G}_n+\theta_k \) are defined via iterated solution of a special kind of functional equation...and that maybe can be linked with your knowledge in this field...

Definition-\( \mathcal{G}_3+\theta_k \) is defined as follow

Quote:I-the constants \( 0 \),\( 1 \),\( -1 \) and \( \pi \), the projection functions, \( \theta_k \) are in \( \mathcal{G}_3+\theta_k \)

II-\( \mathcal{G}_3+\theta_k \) is closed composition and linear integration
in a recursive way we define \( \mathcal{G}_{n+1}+\theta_k \)
Quote:III- \( \mathcal{G}_{n+1}+\theta_k \) contains the functions in \( \mathcal{G}_{n}+\theta_k \)

IV- \( \mathcal{G}_{n+1}+\theta_k \) in we can find all the solutions to the equation (2) in this text ( http://languagelog.ldc.upenn.edu/myl/DK/...oMoore.pdf ) applied to the functions in \( \mathcal{G}_{n}+\theta_k \)

V-\( \mathcal{G}_{n+1}+\theta_k \) is closed under composition and linear integration

\( \theta_k(x):=x^k\theta(x) \) and

\( \theta(x):=0 \) if \( x \le 0 \)
\( \theta(x):=1 \) if \( x \gt 1 \)

Mother Law \(\sigma^+\circ 0=\sigma \circ \sigma^+ \)

\({\rm Grp}_{\rm pt} ({\rm RK}J,G)\cong \mathbb N{\rm Set}_{\rm pt} (J, \Sigma^G)\)
Reply


Possibly Related Threads…
Thread Author Replies Views Last Post
Question Complex Hardy Hierarchy Catullus 3 6,619 11/09/2022, 05:57 PM
Last Post: MphLee
Question Circulation and the Fast-Growing Hierarchy Catullus 20 30,351 09/24/2022, 12:36 AM
Last Post: Catullus
  Iterated compositions Xorter 0 5,508 08/20/2016, 01:19 PM
Last Post: Xorter
  Functional super-iteration and hierarchy of functional hyper-iterations Base-Acid Tetration 24 83,184 05/12/2009, 07:11 AM
Last Post: bo198214
  the logical hierarchy tommy1729 3 12,583 02/08/2009, 10:53 PM
Last Post: bo198214



Users browsing this thread: 1 Guest(s)